Kristen says the cameras keep editing her to make her look like a sour puss!

Why doesEclipse star Kristen Stewart have such a tough time smiling for the cameras? If you ask her, she’ll tell you DOES smile — and she tries really hard to show it! “I feel like the cameras cut to me just as soon as I stop smiling,” Kristen tells Access Hollywood. “I’ve had so many people say to me, ‘Why don’t you just play the part? Go smile, talk about whatever they want you to talk about.’ I do, I really try to do that. I guess I should get a face transplant or something!”

“It totally kills me,” Kristen continues. “People are much better at doing this [smiling] than I am. I’m fine, I’m getting better, but I’m not going to try to force myself to do anything. … I’ve relinquished control. As soon as you sort of just give up and say like ‘alright,’ there’s nothing I can really do about any of this.”

Kristen will have A LOT to smile about when she films the fourth installment of the Twilight saga, Breaking Dawn, which is now going to be broken up into two films. In the movie(s), Kristen and Robert Pattinson‘s characters, Bella and Edward, finally go all the way — and Kristen and Rob are really excited about it.

“They have sex, FINALLY,” Kristen gushes. “They get married and have a kid too.”

And R-Patz can’t WAIT until the bedroom scene! “I’m looking forward to the pillow biting scene!” he admits.